[adding Markus as error maintainer]

On 11/13/2017 09:24 AM, Eric Blake wrote:
> When using error prepend(), it is necessary to end with a space
> in the format string; otherwise, messages come out incorrectly,
> such as when connecting to a socket that hangs up immediately:
> 
> can't open device nbd://localhost:10809/: Failed to read dataUnexpected end-of-file before all bytes were read
> 
> Originally botched in commit e44ed99d, then several more instances
> added in the meantime.
> 
> CC: qemu-stable@nongnu.org
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  nbd/client.c | 50 ++++++++++++++++++++++++++------------------------
>  1 file changed, 26 insertions(+), 24 deletions(-)
> 
> diff --git a/nbd/client.c b/nbd/client.c
> index 1880103d2a..4e15fc484d 100644
> --- a/nbd/client.c
> +++ b/nbd/client.c
> @@ -79,12 +79,12 @@ static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
>      stl_be_p(&req.length, len);
> 
>      if (nbd_write(ioc, &req, sizeof(req), errp) < 0) {
> -        error_prepend(errp, "Failed to send option request header");
> +        error_prepend(errp, "Failed to send option request header: ");

A quick grep of the tree noticed that most (all?) error_prepend()
callers use trailing ": " in their format string.  Should we refactor
that to be done automatically by error_prepend() itself, rather than at
every callsite?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org